This invention relates generally to drive assemblies for use with power-driven implements, such as lawn mowers and the like. More specifically, this invention relates to a simplified and inexpensive yet highly reliable drive assembly of the type including a so-called deadman clutch and brake mechanism for automatically halting rotation of an output or driven member to prevent operator injury.
A variety of drive assemblies including a so-called deadman clutch and/or brake mechanism are known for use with power-driven implements having an engine or motor drive shaft for rotatably driving a tool-carrying driven member. Such mechanisms typically include a control lever or the like mounted in a convenient, exposed position on the implement, wherein the control lever must be grasped and held by the operator to connect the driven member to the engine drive shaft. If the control lever is released for any reason, the mechanism automatically uncouples the driven member from the drive shaft and, if a brake device is provided, quickly stops rotation of the driven member.
Drive assemblies including such clutch and brake mechanisms have been frequently suggested for use with domestic power lawn mowers having an engine for rotatably driving a grass cutting blade at a relatively high rotational speed, wherein this cutting blade has in the past been an all-too-frequent source of serious and sometimes disabling operator injuries occurring primarily when the operator moves away from a safe pushing position behind the mower. Indeed, the relatively high incidence of serious injuries has resulted in governmental safety regulations requiring manufacturers to include automatic clutch/brake mechanisms on domestic lawn mowing equipment.
In the past, clutch and brake mechanisms for lawn mowers have typically comprised relatively complex and expensive devices requiring a relatively large number of mechanical parts, such as centrifugal clutches, multiple disk friction drives, ball or ratchet drives, traction drives, belt drives, band brakes, and the like. However, these prior mechanisms substantially increase the cost of the lawn mower and therefore have not gained market acceptance. Moreover, prior clutch/brake mechanisms have been subject to frequent mechanical failure partially due to the harsh operating environment beneath the mower housing and partially due to an inability to accommodate the requisite driving/braking forces in a compact design which will not increase the overall size of the mower housing.
There exists, therefore, a significant need for a lawn mower drive assembly including a compact and simplified clutch/brake mechanism constructed from a minimum number of inexpensively formed components capable of reliable, long-lived operation in a lawn mower environment. The present invention fulfills this need and provides further related advantages.